乙醇接枝苯乙烯马来酸酐共聚物的合成及其在红霉素肠溶片中的应用

合成了乙醇接枝苯乙烯马来酸酐共聚物,用FT-IR和1HNMR对其结构进行了表征.用该材料对红霉素进行片剂包衣,按照中国药典2005年版检测了红霉素肠溶片的体外释放度.结果显示,自制的红霉素肠溶片达到了中国药典2005年版的要求,溶解时间与市售的红霉素肠溶片相当,具有很好的抗透湿性.该材料的pH敏感性能较好.     

高效体积排阻色谱法测定改性柑橘果胶的分子质量

改性柑橘果胶(MCP)是一种具有抗肿瘤细胞生长、侵袭和转移活性的多糖。由于多糖的分子质量对其活性有很大的影响,因而需要测定其分子质量。选择的色谱条件为：TSK G3000PWXL色谱柱,以50 mmol/L醋酸铵缓冲液为流动相,流速为0.5 mL/min,柱温为40 ℃,样品质量浓度为10 g/L,进样体积为20 μL,示差折光检测器检测。采用Pullulan糖标准品,经校正获得回归方程,通过回归方程计算得到的MCP平均相对分子质量为:Mn为21000,Mp为46000,Mw为43000,Mz为66000。MCP的多分散性指数(PD)为2。该方法具有良好的重现性,而且简便、快速,为MCP的生产工艺、质量控制和组效关系等的研究提供了实用的分析检测手段。     

油-微乳-盐水三相体系中间相微乳液的电子显微研究

利用液态乳液样品的冷冻溶蚀制样技术,对油-微乳-盐水三相体系中间相微乳作了电子显微镜观察,从形态学的角度对这一类型的微乳液的微观形态进行了分析,并结合胶体与界面化学的理论,对中间相微乳液的微组织结构作了一些探讨。     

Improvement in coercivity,thermal stability,and corrosion resistance of sintered Nd-Fe-B magnets with Dy_(80)Ga_(20) intergranular addition

To investigate the coercivity,corrosion resistance,and thermal stability of Nd-Fe-B magnets,their properties were investigated at room and high temperature before and after doping with Dy_(80)Ga_(20)(at.%) powder.The coercivity of the magnets increased from the undoped value of 12.72 kOe to a doped value of 21.44 kOe.A micro-structural analysis indicates that a well-developed core-shell structure forms in the magnets doped with Dy_(80)Ga_(20) powder.The improvement in magnetic properties is believed to be related to the refined and uniform matrix grains,continuous grain boundaries,and a hardened(Nd,Dy)_2Fe_(14)B shell surrounding the matrix grains.Additionally,the doped magnets exhibit an obvious improvement in thermal stability.For the magnets with added Dy_(80)Ga_(20) powder,the temperature coefficients of remanence(α) and coercivity(β) increased to-0.106%℃~(-1) and-0.60%℃~(-1) over the range 20-100 ℃,compared to temperature coefficients of-0.117%℃~(-1)(α) and-0.74%℃~(-1)(β) in the regular magnets without Dy_(80)Ga_(20) powder.The irreversible loss of magnetic flux(Hirr) was investigated at different temperatures.After being exposed to 150 ℃ for 2 h,the Hirr of magnets with 4 wt.%Dy_(80)Ga_(20) decreased by ~95%compared to that of the undoped magnets.The enhanced temperature coefficients and Hirr indicate improved thermal stability in the doped Nd-Fe-B magnets.The intergranular addition of Dy_(80)Ga_(20) also improved the corrosion resistance of the magnets because of the enhanced intergranular phase.In a corrosive atmosphere for 96 h,the mass loss of the sintered magnets with 4 wt.%Dy_(80)Ga_(20) was 2.68 mg/cm~2,less than 10%of that suffered by the undoped magnets(28.1 mg/cm~2).     

引言

2022年是《分析测试学报》创刊40周年.值此不惑之年,《学报》开展了40周年刊庆系列专辑组稿活动. 生物医学分析是通过运用生物学、医学及分析化学的手段,从微观到宏观研究生命系统的状态变化,采用诸如生物质谱进行蛋白质组学、代谢组学等生物大分子、小分子物质分析,生物成像研究细胞器的正常及病理形态的超微结构分析.     

一维链状配合物{[Fe(SO_4)(DPPZ)_2]·H_2O}_n的水热合成及其晶体结构

以FeSO_4和二吡啶[3,2-a: 2',3'-c]并吩嗪(DPPZ)为原料,采用水热法合成了一维链状配位聚合物{[Fe(SO_4)(DPPZ)_2]·H_2O}_n,利用元素分析、红外光谱、X射线单晶衍射和热重分析对其结构进行了表征.该配合物属于单斜晶系,P2_1/m空间群,a=1.3569(3) nm,b=0.6519(13) nm, c=1.7250(3) nm, α=90°,β=111.29(3)°,γ=90°,V=1.4217(5) nm~3,Z=2,d_c=1.713 g/cm~3,μ=0.671 mm~(-1),F(000)=750, R_1=0.0491, wR_2=0.1250.     

Effects of terbium sulfide addition on magnetic properties,microstructure and thermal stability of sintered Nd-Fe--B magnets

To increase coercivity and thermal stability of sintered Nd–Fe–B magnets for high-temperature applications, a novel terbium sulfide powder is added into(Pr_(0.25)Nd_(0.75))_(30.6)Cu_(0.15)Fe_(bal)B_1(wt.%) basic magnets. The effects of the addition of terbium sulfide on magnetic properties, microstructure, and thermal stability of sintered Nd–Fe–B magnets are investigated.The experimental results show that by adding 3 wt.% Tb_2S_3, the coercivity of the magnet is remarkably increased by about 54% without a considerable reduction in remanence and maximum energy product. By means of the electron probe microanalyzer(EPMA) technology, it is observed that Tb is mainly present in the outer region of 2:14:1 matrix grains and forms a well-developed Tb-shell phase, resulting in enhancement of HA, which accounts for the coercivity enhancement.Moreover, compared with Tb_2S_3-free magnets, the reversible temperature coefficients of remanence(α) and coercivity(β) and the irreversible flux loss of magnetic flow(hirr) values of Tb_2S_3-added magnets are improved, indicating that the thermal stability of the magnets is also effectively improved.     

Decline of nucleation in the heating process with a high heating rate

The effect of the heating rate on the nucleation of metallic glass in a rapid heating process starting from the glass transition temperature is investigated. The critical nucleus radius increases with the increase of the temperature of the undercooling liquid. If the increment rate of the critical nucleus radius, owing to the heating process, is higher than the growth rate of the nuclei, the nuclei generated at the low temperature will become the embryos at the high temperature. This means that the high heating rate can make no nucleation happen in the heating process. In consideration of the interfacial energy, the growth rate of the nuclei increases with the increase of their size and the growth rate of the critical nucleus is zero. Thus, the lower heating rate can also make the nuclei decline partially. Finally, this theory is used to analyze the nucleation process during laser remelting metallic glass.     

抑制地面反射影响的高功率微波辐射场测量方法

在对空气-地面分层媒质中微波传播与反射理论分析的基础上,研究了地面反射对测点处不同垂直高度电场分布的影响,推导得到了电场分布随垂直高度变化曲线的振荡周期理论计算公式,针对高功率微波源总功率测量,提出了一种双天线阵列抑制地面反射影响的高功率微波辐射场测量方法,通过数值计算、低功率连续波实验、大功率短脉冲实验等进一步验证了理论公式的正确性,以及双天线阵列抑制地面反射影响方法的可行性。结果表明,与单接收天线相比,双天线阵列法可将地面反射影响由原有的4dB降低至0.6dB以下,从而有效减小了高功率微波辐射场的测量不确定度,为高功率微波源总功率准确测量奠定了基础。     

单边核磁共振传感器研究及其应用

单边核磁共振(single-sided NMR)传感器具有体积小、造价低和结构开放等特点,特别适用于大型样品的现场无损检测,具有广阔的应用前景.该文介绍了一种均匀度较高的单边核磁共振传感器,在10 mm×10 mm的水平目标区域内,静态磁场均匀度为338×10–6,在垂直方向上静态磁场具有4.6 T/m的恒定梯度.结合该磁场分布的梯度特性,提出了一种基于快速傅里叶变换和带通滤波处理的回波信号处理方法,可提取薄层样品的核磁共振信号,从而实现对样品纵深方向的高分辨率一维测量(分辨率达到50?m).最后使用该传感器对复合绝缘子高分子聚合物、液体的扩散行为,以及植物叶片的枯萎过程进行了测量.展现了该方法在高分子材料分析、液体测量以及农业应用方面的潜力.